versions is now available for the following functions/calculations:
TopN Mode;
Calculated using the Aggr () function;
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VisualizationShow dashboard items fullscreenEnd users can now expand dashboard items to populate the entire dashboard. Supported platforms include: WINFORMS,WPF and Web Dashboard (ASP. Webforms,asp.net mvc,asp.net Core and client).===============================================================Dev
functions in the Sparkcontext class TextfileTo load the processed data, the most commonly used textfile is actually generating Hadooprdd, as the starting Rdd /** * Read a text file from HDFS, a local file system (available in all nodes), or any * hadoop-supported file sys Tem URI, and return it as an RDD of Strings. */ defTextfile (path:string, minpartitions:int = defaultminpartitions): rdd[string] = {assertnotstopped () HadoopFile (Pat H, Classof[textinputformat], classof[longwritable], Cl
. Data skew Solution
2.1 parameter adjustment:
Hive. Map. aggr = true
Partial aggregation on map, equivalent to combiner
Hive. groupby. skewindata= True
Load Balancing is performed when data skew occurs. When the option is set to true, the generated query plan has two Mr Jobs. In the first Mr job, the map output result set is randomly distributed to reduce. Each reduce performs partial aggregation and outputs the result, in this way, the sam
SYS_STU # S # WF25Z # QAHIHE # MOFFMM_ SQL> exec dbms_stats.gather_table_stats ('sh', 'customer', METHOD_OPT =>' FOR ALL Columns size 1, for columns cust_state_province size 250, for columns country_id size 250 '); PL/SQL process completed successfully. SQL> select table_name, column_name, histogram from user_tab_col_statistics where table_name = 'customer' AND column_name like 'sys % '; TABLE_NAME COLUMN_NAME HISTOGRAM partition ---------------------------- --------------- MERs SYS_STU # S # W
Basic aggregation -- Common Aggregate functions count, sum, AVG, Max, min -- Aggregate functions cannot be nested, for example, AVG (count (*) error! Set hive. map. aggr = true; -- pre-aggregation on the Mapper end improves performance, but consumes a lot of memory # Note: do not directly Select fields that are not present in the group by clause; otherwise, the why? Select name, gender_age.gender, count (*) as row_cnt -- error! From employeegroup by g
of processing.Package mice, using the chain equation for multivariate interpolation, can deal with the data loss of mixed variable type, automatically generate the Predictor variables of filling variables, is an important tool to deal with missing values. > Library (MICE) > Data$price=replace (Price,price>5,na) > Md.pattern (data) Price salary City5 1 1 0 13 0 1 0 24 1 0 0 23 4 12 19The "1" in the output showsno missing data, and "0" indicates that there is missing data. The 1th column, line 1t
#识别缺失值install. Packages ("Vim") data (sleep,package= "vim") #列出没有缺失值的行sleep [Complete.cases (Sleep),]# Lists rows sleep[!complete.cases (sleep) with one or more missing values,] #有多少个缺失值sum (Is.na (sleep$dream)) #sleep The data for a percentage of the $dream is mean with missing values ( Is.na (Sleep$dream)) #数据集中多个行包含缺失值mean (!complete.cases (Sleep)) #探索缺失值install. Packages ("mice") the library (MICE) data ( Sleep,package= "Vim") Md.pattern (Sleep) #图形探索library ("Vim")
Recently received some real data, the data contains a lot of missing values, how to deal with the missing value, better for us to do data analysis, more efficient modeling, reduce the test set on the forecast analysis of deviation, of course, the smaller the deviation we must be happier. Data preparation
I'm using a geographical sample of data with coordinates, various material components (CA,N,P, etc.).
There are several ways to test for missing data. First type:
Library (VIM)
indicate that the bound variable is not wellSortsNumber of ordersw/a MB processedThe amount of data processed in the unit MB w/a workarea Workarea combined with in-memory sort%, sorts (disk) PGA Aggr look togetherLogonNumber of log-in databasesExecutesNumber of executionsRollbacksRollback timesTransactionsNumber of transactionsInstance efficiency percentages (Target 100%)~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~Buffer Nowait%: 100.00 Redo Nowait%
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